From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262086AbVFQTmt (ORCPT ); Fri, 17 Jun 2005 15:42:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262074AbVFQTkG (ORCPT ); Fri, 17 Jun 2005 15:40:06 -0400 Received: from ylpvm15-ext.prodigy.net ([207.115.57.46]:147 "EHLO ylpvm15.prodigy.net") by vger.kernel.org with ESMTP id S262080AbVFQTjk (ORCPT ); Fri, 17 Jun 2005 15:39:40 -0400 X-ORBL: [69.107.32.110] From: David Brownell To: Matt Mackall Subject: Re: usbnet ethernet duplex issue? Date: Fri, 17 Jun 2005 12:39:24 -0700 User-Agent: KMail/1.7.1 Cc: David Brownell , linux-kernel , linux-usb-devel@lists.sourceforge.net References: <20050617192715.GK27572@waste.org> In-Reply-To: <20050617192715.GK27572@waste.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200506171239.25258.david-b@pacbell.net> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Friday 17 June 2005 12:27 pm, Matt Mackall wrote: > > So the question is, what's up with duplex? Everything I can find about > the hardware (including the ASIX datasheet) claims it's full-duplex > capable but aside from the error counters, it's really behaving like a > half-duplex device. Well, USB itself is half duplex, but that wouldn't explain the issue you're seeing. Maybe David Hollis or Phil Chang, who've both worked with the ASIX parts, can cast some light on their quirks. This is on a 2.6 kernel, I hope ... 2.4 kernels have packet queues a bit too high up in the stack to get any real I/O overlap. I know that when I've done "ttcp" Linux-to-Linux using a net2280 PCI card [1] using CDC Ethernet protocols, I can get a bidirectional transfer rate of around 25 Mbyte/sec (maybe a bit more, I forget; that's untuned), so the bottleneck isn't the network or USB stacks. - Dave [1] http://store.yahoo.com/plxtech/net2280evb.html